Initial checkin of gRPC to third_party/

third_party/grpc/src/core/channel/client_channel.c

+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/channel/client_channel.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/channel/channel_args.h"
+#include "src/core/channel/connected_channel.h"
+#include "src/core/channel/subchannel_call_holder.h"
+#include "src/core/iomgr/iomgr.h"
+#include "src/core/profiling/timers.h"
+#include "src/core/support/string.h"
+#include "src/core/surface/channel.h"
+#include "src/core/transport/connectivity_state.h"
+
+/* Client channel implementation */
+
+typedef grpc_subchannel_call_holder call_data;
+
+typedef struct client_channel_channel_data {
+  /** resolver for this channel */
+  grpc_resolver *resolver;
+  /** have we started resolving this channel */
+  int started_resolving;
+
+  /** mutex protecting client configuration, including all
+      variables below in this data structure */
+  gpr_mu mu_config;
+  /** currently active load balancer - guarded by mu_config */
+  grpc_lb_policy *lb_policy;
+  /** incoming configuration - set by resolver.next
+      guarded by mu_config */
+  grpc_client_config *incoming_configuration;
+  /** a list of closures that are all waiting for config to come in */
+  grpc_closure_list waiting_for_config_closures;
+  /** resolver callback */
+  grpc_closure on_config_changed;
+  /** connectivity state being tracked */
+  grpc_connectivity_state_tracker state_tracker;
+  /** when an lb_policy arrives, should we try to exit idle */
+  int exit_idle_when_lb_policy_arrives;
+  /** owning stack */
+  grpc_channel_stack *owning_stack;
+  /** interested parties (owned) */
+  grpc_pollset_set *interested_parties;
+} channel_data;
+
+/** We create one watcher for each new lb_policy that is returned from a
+   resolver,
+    to watch for state changes from the lb_policy. When a state change is seen,
+   we
+    update the channel, and create a new watcher */
+typedef struct {
+  channel_data *chand;
+  grpc_closure on_changed;
+  grpc_connectivity_state state;
+  grpc_lb_policy *lb_policy;
+} lb_policy_connectivity_watcher;
+
+typedef struct {
+  grpc_closure closure;
+  grpc_call_element *elem;
+} waiting_call;
+
+static char *cc_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
+  return grpc_subchannel_call_holder_get_peer(exec_ctx, elem->call_data);
+}
+
+static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
+                                         grpc_call_element *elem,
+                                         grpc_transport_stream_op *op) {
+  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
+  grpc_subchannel_call_holder_perform_op(exec_ctx, elem->call_data, op);
+}
+
+static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
+                            grpc_lb_policy *lb_policy,
+                            grpc_connectivity_state current_state);
+
+static void on_lb_policy_state_changed_locked(
+    grpc_exec_ctx *exec_ctx, lb_policy_connectivity_watcher *w) {
+  grpc_connectivity_state publish_state = w->state;
+  /* check if the notification is for a stale policy */
+  if (w->lb_policy != w->chand->lb_policy) return;
+
+  if (publish_state == GRPC_CHANNEL_FATAL_FAILURE &&
+      w->chand->resolver != NULL) {
+    publish_state = GRPC_CHANNEL_TRANSIENT_FAILURE;
+    grpc_resolver_channel_saw_error(exec_ctx, w->chand->resolver);
+    GRPC_LB_POLICY_UNREF(exec_ctx, w->chand->lb_policy, "channel");
+    w->chand->lb_policy = NULL;
+  }
+  grpc_connectivity_state_set(exec_ctx, &w->chand->state_tracker, publish_state,
+                              "lb_changed");
+  if (w->state != GRPC_CHANNEL_FATAL_FAILURE) {
+    watch_lb_policy(exec_ctx, w->chand, w->lb_policy, w->state);
+  }
+}
+
+static void on_lb_policy_state_changed(grpc_exec_ctx *exec_ctx, void *arg,
+                                       bool iomgr_success) {
+  lb_policy_connectivity_watcher *w = arg;
+
+  gpr_mu_lock(&w->chand->mu_config);
+  on_lb_policy_state_changed_locked(exec_ctx, w);
+  gpr_mu_unlock(&w->chand->mu_config);
+
+  GRPC_CHANNEL_STACK_UNREF(exec_ctx, w->chand->owning_stack, "watch_lb_policy");
+  gpr_free(w);
+}
+
+static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
+                            grpc_lb_policy *lb_policy,
+                            grpc_connectivity_state current_state) {
+  lb_policy_connectivity_watcher *w = gpr_malloc(sizeof(*w));
+  GRPC_CHANNEL_STACK_REF(chand->owning_stack, "watch_lb_policy");
+
+  w->chand = chand;
+  grpc_closure_init(&w->on_changed, on_lb_policy_state_changed, w);
+  w->state = current_state;
+  w->lb_policy = lb_policy;
+  grpc_lb_policy_notify_on_state_change(exec_ctx, lb_policy, &w->state,
+                                        &w->on_changed);
+}
+
+static void cc_on_config_changed(grpc_exec_ctx *exec_ctx, void *arg,
+                                 bool iomgr_success) {
+  channel_data *chand = arg;
+  grpc_lb_policy *lb_policy = NULL;
+  grpc_lb_policy *old_lb_policy;
+  grpc_connectivity_state state = GRPC_CHANNEL_TRANSIENT_FAILURE;
+  int exit_idle = 0;
+
+  if (chand->incoming_configuration != NULL) {
+    lb_policy = grpc_client_config_get_lb_policy(chand->incoming_configuration);
+    if (lb_policy != NULL) {
+      GRPC_LB_POLICY_REF(lb_policy, "channel");
+      GRPC_LB_POLICY_REF(lb_policy, "config_change");
+      state = grpc_lb_policy_check_connectivity(exec_ctx, lb_policy);
+    }
+
+    grpc_client_config_unref(exec_ctx, chand->incoming_configuration);
+  }
+
+  chand->incoming_configuration = NULL;
+
+  if (lb_policy != NULL) {
+    grpc_pollset_set_add_pollset_set(exec_ctx, lb_policy->interested_parties,
+                                     chand->interested_parties);
+  }
+
+  gpr_mu_lock(&chand->mu_config);
+  old_lb_policy = chand->lb_policy;
+  chand->lb_policy = lb_policy;
+  if (lb_policy != NULL || chand->resolver == NULL /* disconnected */) {
+    grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures,
+                               NULL);
+  }
+  if (lb_policy != NULL && chand->exit_idle_when_lb_policy_arrives) {
+    GRPC_LB_POLICY_REF(lb_policy, "exit_idle");
+    exit_idle = 1;
+    chand->exit_idle_when_lb_policy_arrives = 0;
+  }
+
+  if (iomgr_success && chand->resolver) {
+    grpc_connectivity_state_set(exec_ctx, &chand->state_tracker, state,
+                                "new_lb+resolver");
+    if (lb_policy != NULL) {
+      watch_lb_policy(exec_ctx, chand, lb_policy, state);
+    }
+    GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
+    grpc_resolver_next(exec_ctx, chand->resolver,
+                       &chand->incoming_configuration,
+                       &chand->on_config_changed);
+    gpr_mu_unlock(&chand->mu_config);
+  } else {
+    if (chand->resolver != NULL) {
+      grpc_resolver_shutdown(exec_ctx, chand->resolver);
+      GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
+      chand->resolver = NULL;
+    }
+    grpc_connectivity_state_set(exec_ctx, &chand->state_tracker,
+                                GRPC_CHANNEL_FATAL_FAILURE, "resolver_gone");
+    gpr_mu_unlock(&chand->mu_config);
+  }
+
+  if (exit_idle) {
+    grpc_lb_policy_exit_idle(exec_ctx, lb_policy);
+    GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "exit_idle");
+  }
+
+  if (old_lb_policy != NULL) {
+    grpc_pollset_set_del_pollset_set(
+        exec_ctx, old_lb_policy->interested_parties, chand->interested_parties);
+    GRPC_LB_POLICY_UNREF(exec_ctx, old_lb_policy, "channel");
+  }
+
+  if (lb_policy != NULL) {
+    GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "config_change");
+  }
+
+  GRPC_CHANNEL_STACK_UNREF(exec_ctx, chand->owning_stack, "resolver");
+}
+
+static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
+                                  grpc_channel_element *elem,
+                                  grpc_transport_op *op) {
+  channel_data *chand = elem->channel_data;
+
+  grpc_exec_ctx_enqueue(exec_ctx, op->on_consumed, true, NULL);
+
+  GPR_ASSERT(op->set_accept_stream == false);
+  if (op->bind_pollset != NULL) {
+    grpc_pollset_set_add_pollset(exec_ctx, chand->interested_parties,
+                                 op->bind_pollset);
+  }
+
+  gpr_mu_lock(&chand->mu_config);
+  if (op->on_connectivity_state_change != NULL) {
+    grpc_connectivity_state_notify_on_state_change(
+        exec_ctx, &chand->state_tracker, op->connectivity_state,
+        op->on_connectivity_state_change);
+    op->on_connectivity_state_change = NULL;
+    op->connectivity_state = NULL;
+  }
+
+  if (op->send_ping != NULL) {
+    if (chand->lb_policy == NULL) {
+      grpc_exec_ctx_enqueue(exec_ctx, op->send_ping, false, NULL);
+    } else {
+      grpc_lb_policy_ping_one(exec_ctx, chand->lb_policy, op->send_ping);
+      op->bind_pollset = NULL;
+    }
+    op->send_ping = NULL;
+  }
+
+  if (op->disconnect && chand->resolver != NULL) {
+    grpc_connectivity_state_set(exec_ctx, &chand->state_tracker,
+                                GRPC_CHANNEL_FATAL_FAILURE, "disconnect");
+    grpc_resolver_shutdown(exec_ctx, chand->resolver);
+    GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
+    chand->resolver = NULL;
+    if (chand->lb_policy != NULL) {
+      grpc_pollset_set_del_pollset_set(exec_ctx,
+                                       chand->lb_policy->interested_parties,
+                                       chand->interested_parties);
+      GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
+      chand->lb_policy = NULL;
+    }
+  }
+  gpr_mu_unlock(&chand->mu_config);
+}
+
+typedef struct {
+  grpc_metadata_batch *initial_metadata;
+  grpc_connected_subchannel **connected_subchannel;
+  grpc_closure *on_ready;
+  grpc_call_element *elem;
+  grpc_closure closure;
+} continue_picking_args;
+
+static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
+                              grpc_metadata_batch *initial_metadata,
+                              grpc_connected_subchannel **connected_subchannel,
+                              grpc_closure *on_ready);
+
+static void continue_picking(grpc_exec_ctx *exec_ctx, void *arg, bool success) {
+  continue_picking_args *cpa = arg;
+  if (!success) {
+    grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, false, NULL);
+  } else if (cpa->connected_subchannel == NULL) {
+    /* cancelled, do nothing */
+  } else if (cc_pick_subchannel(exec_ctx, cpa->elem, cpa->initial_metadata,
+                                cpa->connected_subchannel, cpa->on_ready)) {
+    grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, true, NULL);
+  }
+  gpr_free(cpa);
+}
+
+static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *elemp,
+                              grpc_metadata_batch *initial_metadata,
+                              grpc_connected_subchannel **connected_subchannel,
+                              grpc_closure *on_ready) {
+  grpc_call_element *elem = elemp;
+  channel_data *chand = elem->channel_data;
+  call_data *calld = elem->call_data;
+  continue_picking_args *cpa;
+  grpc_closure *closure;
+
+  GPR_ASSERT(connected_subchannel);
+
+  gpr_mu_lock(&chand->mu_config);
+  if (initial_metadata == NULL) {
+    if (chand->lb_policy != NULL) {
+      grpc_lb_policy_cancel_pick(exec_ctx, chand->lb_policy,
+                                 connected_subchannel);
+    }
+    for (closure = chand->waiting_for_config_closures.head; closure != NULL;
+         closure = grpc_closure_next(closure)) {
+      cpa = closure->cb_arg;
+      if (cpa->connected_subchannel == connected_subchannel) {
+        cpa->connected_subchannel = NULL;
+        grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, false, NULL);
+      }
+    }
+    gpr_mu_unlock(&chand->mu_config);
+    return 1;
+  }
+  if (chand->lb_policy != NULL) {
+    grpc_lb_policy *lb_policy = chand->lb_policy;
+    int r;
+    GRPC_LB_POLICY_REF(lb_policy, "cc_pick_subchannel");
+    gpr_mu_unlock(&chand->mu_config);
+    r = grpc_lb_policy_pick(exec_ctx, lb_policy, calld->pollset,
+                            initial_metadata, connected_subchannel, on_ready);
+    GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "cc_pick_subchannel");
+    return r;
+  }
+  if (chand->resolver != NULL && !chand->started_resolving) {
+    chand->started_resolving = 1;
+    GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
+    grpc_resolver_next(exec_ctx, chand->resolver,
+                       &chand->incoming_configuration,
+                       &chand->on_config_changed);
+  }
+  cpa = gpr_malloc(sizeof(*cpa));
+  cpa->initial_metadata = initial_metadata;
+  cpa->connected_subchannel = connected_subchannel;
+  cpa->on_ready = on_ready;
+  cpa->elem = elem;
+  grpc_closure_init(&cpa->closure, continue_picking, cpa);
+  grpc_closure_list_add(&chand->waiting_for_config_closures, &cpa->closure, 1);
+  gpr_mu_unlock(&chand->mu_config);
+  return 0;
+}
+
+/* Constructor for call_data */
+static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                           grpc_call_element_args *args) {
+  grpc_subchannel_call_holder_init(elem->call_data, cc_pick_subchannel, elem,
+                                   args->call_stack);
+}
+
+/* Destructor for call_data */
+static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
+                              grpc_call_element *elem) {
+  grpc_subchannel_call_holder_destroy(exec_ctx, elem->call_data);
+}
+
+/* Constructor for channel_data */
+static void init_channel_elem(grpc_exec_ctx *exec_ctx,
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  channel_data *chand = elem->channel_data;
+
+  memset(chand, 0, sizeof(*chand));
+
+  GPR_ASSERT(args->is_last);
+  GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
+
+  gpr_mu_init(&chand->mu_config);
+  grpc_closure_init(&chand->on_config_changed, cc_on_config_changed, chand);
+  chand->owning_stack = args->channel_stack;
+
+  grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
+                               "client_channel");
+  chand->interested_parties = grpc_pollset_set_create();
+}
+
+/* Destructor for channel_data */
+static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_element *elem) {
+  channel_data *chand = elem->channel_data;
+
+  if (chand->resolver != NULL) {
+    grpc_resolver_shutdown(exec_ctx, chand->resolver);
+    GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
+  }
+  if (chand->lb_policy != NULL) {
+    grpc_pollset_set_del_pollset_set(exec_ctx,
+                                     chand->lb_policy->interested_parties,
+                                     chand->interested_parties);
+    GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
+  }
+  grpc_connectivity_state_destroy(exec_ctx, &chand->state_tracker);
+  grpc_pollset_set_destroy(chand->interested_parties);
+  gpr_mu_destroy(&chand->mu_config);
+}
+
+static void cc_set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                           grpc_pollset *pollset) {
+  call_data *calld = elem->call_data;
+  calld->pollset = pollset;
+}
+
+const grpc_channel_filter grpc_client_channel_filter = {
+    cc_start_transport_stream_op, cc_start_transport_op, sizeof(call_data),
+    init_call_elem, cc_set_pollset, destroy_call_elem, sizeof(channel_data),
+    init_channel_elem, destroy_channel_elem, cc_get_peer, "client-channel",
+};
+
+void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,
+                                      grpc_channel_stack *channel_stack,
+                                      grpc_resolver *resolver) {
+  /* post construction initialization: set the transport setup pointer */
+  grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
+  channel_data *chand = elem->channel_data;
+  gpr_mu_lock(&chand->mu_config);
+  GPR_ASSERT(!chand->resolver);
+  chand->resolver = resolver;
+  GRPC_RESOLVER_REF(resolver, "channel");
+  if (!grpc_closure_list_empty(chand->waiting_for_config_closures) ||
+      chand->exit_idle_when_lb_policy_arrives) {
+    chand->started_resolving = 1;
+    GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
+    grpc_resolver_next(exec_ctx, resolver, &chand->incoming_configuration,
+                       &chand->on_config_changed);
+  }
+  gpr_mu_unlock(&chand->mu_config);
+}
+
+grpc_connectivity_state grpc_client_channel_check_connectivity_state(
+    grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, int try_to_connect) {
+  channel_data *chand = elem->channel_data;
+  grpc_connectivity_state out;
+  gpr_mu_lock(&chand->mu_config);
+  out = grpc_connectivity_state_check(&chand->state_tracker);
+  if (out == GRPC_CHANNEL_IDLE && try_to_connect) {
+    if (chand->lb_policy != NULL) {
+      grpc_lb_policy_exit_idle(exec_ctx, chand->lb_policy);
+    } else {
+      chand->exit_idle_when_lb_policy_arrives = 1;
+      if (!chand->started_resolving && chand->resolver != NULL) {
+        GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
+        chand->started_resolving = 1;
+        grpc_resolver_next(exec_ctx, chand->resolver,
+                           &chand->incoming_configuration,
+                           &chand->on_config_changed);
+      }
+    }
+  }
+  gpr_mu_unlock(&chand->mu_config);
+  return out;
+}
+
+typedef struct {
+  channel_data *chand;
+  grpc_pollset *pollset;
+  grpc_closure *on_complete;
+  grpc_closure my_closure;
+} external_connectivity_watcher;
+
+static void on_external_watch_complete(grpc_exec_ctx *exec_ctx, void *arg,
+                                       bool iomgr_success) {
+  external_connectivity_watcher *w = arg;
+  grpc_closure *follow_up = w->on_complete;
+  grpc_pollset_set_del_pollset(exec_ctx, w->chand->interested_parties,
+                               w->pollset);
+  GRPC_CHANNEL_STACK_UNREF(exec_ctx, w->chand->owning_stack,
+                           "external_connectivity_watcher");
+  gpr_free(w);
+  follow_up->cb(exec_ctx, follow_up->cb_arg, iomgr_success);
+}
+
+void grpc_client_channel_watch_connectivity_state(
+    grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, grpc_pollset *pollset,
+    grpc_connectivity_state *state, grpc_closure *on_complete) {
+  channel_data *chand = elem->channel_data;
+  external_connectivity_watcher *w = gpr_malloc(sizeof(*w));
+  w->chand = chand;
+  w->pollset = pollset;
+  w->on_complete = on_complete;
+  grpc_pollset_set_add_pollset(exec_ctx, chand->interested_parties, pollset);
+  grpc_closure_init(&w->my_closure, on_external_watch_complete, w);
+  GRPC_CHANNEL_STACK_REF(w->chand->owning_stack,
+                         "external_connectivity_watcher");
+  gpr_mu_lock(&chand->mu_config);
+  grpc_connectivity_state_notify_on_state_change(
+      exec_ctx, &chand->state_tracker, state, &w->my_closure);
+  gpr_mu_unlock(&chand->mu_config);
+}